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Old 02-15-2008, 06:50 PM   #1
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Default VATS differences??

I picked up a 1997 PCM from the junkyard, just to check my connections before plugging in the "proper" PCM. Now, according to the 1993 schematics, VATS will ground out the "fuel enable" input to the PCM. DO the newer PCMs follow the same theory of operation, or do they have a method instead of the ground-out?

Reason i ask is I got all the circuits to work...except the injectors are not pulsing. And the 1993 VATS system is connected to the fuel enable input of the 1997 PCM.
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Old 02-15-2008, 08:58 PM   #2
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99 FSM says the module provides a ground to enable the starter but sends a "proper pulse width modulated (PWM)" signal to enable fuel delivery.
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Old 02-15-2008, 09:18 PM   #3
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Ah-hah!

That 'splains alot. This means OBD2 PCMs are not compatible with early-style VATS. Looks like the only way for me to go is to have the VATS turned off in the PCM options when it'* tuning time...no big deal.

Thanks TT...you saved me alot of headache and worry
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